This invention relates generally to semiconductor processing technology, and more particularly the invention relates to a method of fabricating electrically-programmable elements in a semiconductor integrated circuit.
Disclosed in U.S. Pat. No. 4,590,589 is an electrically-programmable element in which a surface layer of a doped semiconductor region is amorphotized by ion implantation to thereby increase the resistance of the surface layer. The resistance can be significantly reduced by applying a sufficient programming voltage to the surface layer and thereby crystallize the amorphous structure of the surface layer.
Some semiconductor integrated circuits rely on junction isolation to electrically isolate circuit components in the circuit. In such devices, a region of one conductivity type is formed in a semiconductor body of opposite conductivity type, and the junction therebetween is reverse-biased to electrically isolate the doped region. As integrated circuit dimensions become smaller, the vertical depth of the doped regions becomes smaller. Then in forming an amorphotized surface layer on the doped region, the crystal damage induced by the amorphotizing implant can propagate to the underlying P-N junction and result in unwanted current leakage when the junction is reverse-biased.